SI-8129 Make Object#== override Any#==

And the same for !=

If we tried to declare these signatures in non-fictional classes,
we would be chastised about collapsing into the "same signature after
erasure".

This will have an influence of typing, as the typechecking of
arguments is sensitive to overloading: if multiple variants are
feasible, the argument will be typechecked with a wildcard expected
type. So people inspecting the types of the arguments to `==` before
this change might have seen an interesting type for
`if (true) x else y`, but now the `If` will have type `Any`, as we
don't need to calculate the LUB.

I've left a TODO to note that we should really make `Any#{==, !=}`
non-final and include a final override in `AnyVal`. But I don't think
that is particularly urgent.

1 files changed, 1 insertions, 3 deletions

diff --git a/test/files/presentation/completion-implicit-chained.check b/test/files/presentation/completion-implicit-chained.check
index f9d77f7a53..c583b7877c 100644
--- a/test/files/presentation/completion-implicit-chained.check
+++ b/test/files/presentation/completion-implicit-chained.check
@@ -3,7 +3,7 @@ reload: Completions.scala
 askTypeCompletion at Completions.scala(11,16)
 ================================================================================
 [response] askTypeCompletion at (11,16)
-retrieved 24 members
+retrieved 22 members
 [inaccessible] protected[package lang] def clone(): Object
 [inaccessible] protected[package lang] def finalize(): Unit
 def equals(x$1: Any): Boolean
@@ -11,10 +11,8 @@ def hashCode(): Int
 def map(x: Int => Int)(implicit a: DummyImplicit): test.O.type
 def toString(): String
 final def !=(x$1: Any): Boolean
-final def !=(x$1: AnyRef): Boolean
 final def ##(): Int
 final def ==(x$1: Any): Boolean
-final def ==(x$1: AnyRef): Boolean
 final def asInstanceOf[T0]: T0
 final def eq(x$1: AnyRef): Boolean
 final def isInstanceOf[T0]: Boolean